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1/* SPDX-License-Identifier: GPL-2.0-or-later */2/*3 * AEAD: Authenticated Encryption with Associated Data4 * 5 * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>6 */7 8#ifndef _CRYPTO_AEAD_H9#define _CRYPTO_AEAD_H10 11#include <linux/atomic.h>12#include <linux/container_of.h>13#include <linux/crypto.h>14#include <linux/slab.h>15#include <linux/types.h>16 17/**18 * DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API19 *20 * The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD21 * (listed as type "aead" in /proc/crypto)22 *23 * The most prominent examples for this type of encryption is GCM and CCM.24 * However, the kernel supports other types of AEAD ciphers which are defined25 * with the following cipher string:26 *27 * authenc(keyed message digest, block cipher)28 *29 * For example: authenc(hmac(sha256), cbc(aes))30 *31 * The example code provided for the symmetric key cipher operation applies32 * here as well. Naturally all *skcipher* symbols must be exchanged the *aead*33 * pendants discussed in the following. In addition, for the AEAD operation,34 * the aead_request_set_ad function must be used to set the pointer to the35 * associated data memory location before performing the encryption or36 * decryption operation. Another deviation from the asynchronous block cipher37 * operation is that the caller should explicitly check for -EBADMSG of the38 * crypto_aead_decrypt. That error indicates an authentication error, i.e.39 * a breach in the integrity of the message. In essence, that -EBADMSG error40 * code is the key bonus an AEAD cipher has over "standard" block chaining41 * modes.42 *43 * Memory Structure:44 *45 * The source scatterlist must contain the concatenation of46 * associated data || plaintext or ciphertext.47 *48 * The destination scatterlist has the same layout, except that the plaintext49 * (resp. ciphertext) will grow (resp. shrink) by the authentication tag size50 * during encryption (resp. decryption). The authentication tag is generated51 * during the encryption operation and appended to the ciphertext. During52 * decryption, the authentication tag is consumed along with the ciphertext and53 * used to verify the integrity of the plaintext and the associated data.54 *55 * In-place encryption/decryption is enabled by using the same scatterlist56 * pointer for both the source and destination.57 *58 * Even in the out-of-place case, space must be reserved in the destination for59 * the associated data, even though it won't be written to. This makes the60 * in-place and out-of-place cases more consistent. It is permissible for the61 * "destination" associated data to alias the "source" associated data.62 *63 * As with the other scatterlist crypto APIs, zero-length scatterlist elements64 * are not allowed in the used part of the scatterlist. Thus, if there is no65 * associated data, the first element must point to the plaintext/ciphertext.66 *67 * To meet the needs of IPsec, a special quirk applies to rfc4106, rfc4309,68 * rfc4543, and rfc7539esp ciphers. For these ciphers, the final 'ivsize' bytes69 * of the associated data buffer must contain a second copy of the IV. This is70 * in addition to the copy passed to aead_request_set_crypt(). These two IV71 * copies must not differ; different implementations of the same algorithm may72 * behave differently in that case. Note that the algorithm might not actually73 * treat the IV as associated data; nevertheless the length passed to74 * aead_request_set_ad() must include it.75 */76 77struct crypto_aead;78struct scatterlist;79 80/**81 * struct aead_request - AEAD request82 * @base: Common attributes for async crypto requests83 * @assoclen: Length in bytes of associated data for authentication84 * @cryptlen: Length of data to be encrypted or decrypted85 * @iv: Initialisation vector86 * @src: Source data87 * @dst: Destination data88 * @__ctx: Start of private context data89 */90struct aead_request {91 struct crypto_async_request base;92 93 unsigned int assoclen;94 unsigned int cryptlen;95 96 u8 *iv;97 98 struct scatterlist *src;99 struct scatterlist *dst;100 101 void *__ctx[] CRYPTO_MINALIGN_ATTR;102};103 104/**105 * struct aead_alg - AEAD cipher definition106 * @maxauthsize: Set the maximum authentication tag size supported by the107 * transformation. A transformation may support smaller tag sizes.108 * As the authentication tag is a message digest to ensure the109 * integrity of the encrypted data, a consumer typically wants the110 * largest authentication tag possible as defined by this111 * variable.112 * @setauthsize: Set authentication size for the AEAD transformation. This113 * function is used to specify the consumer requested size of the114 * authentication tag to be either generated by the transformation115 * during encryption or the size of the authentication tag to be116 * supplied during the decryption operation. This function is also117 * responsible for checking the authentication tag size for118 * validity.119 * @setkey: see struct skcipher_alg120 * @encrypt: see struct skcipher_alg121 * @decrypt: see struct skcipher_alg122 * @ivsize: see struct skcipher_alg123 * @chunksize: see struct skcipher_alg124 * @init: Initialize the cryptographic transformation object. This function125 * is used to initialize the cryptographic transformation object.126 * This function is called only once at the instantiation time, right127 * after the transformation context was allocated. In case the128 * cryptographic hardware has some special requirements which need to129 * be handled by software, this function shall check for the precise130 * requirement of the transformation and put any software fallbacks131 * in place.132 * @exit: Deinitialize the cryptographic transformation object. This is a133 * counterpart to @init, used to remove various changes set in134 * @init.135 * @base: Definition of a generic crypto cipher algorithm.136 *137 * All fields except @ivsize is mandatory and must be filled.138 */139struct aead_alg {140 int (*setkey)(struct crypto_aead *tfm, const u8 *key,141 unsigned int keylen);142 int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);143 int (*encrypt)(struct aead_request *req);144 int (*decrypt)(struct aead_request *req);145 int (*init)(struct crypto_aead *tfm);146 void (*exit)(struct crypto_aead *tfm);147 148 unsigned int ivsize;149 unsigned int maxauthsize;150 unsigned int chunksize;151 152 struct crypto_alg base;153};154 155struct crypto_aead {156 unsigned int authsize;157 unsigned int reqsize;158 159 struct crypto_tfm base;160};161 162static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)163{164 return container_of(tfm, struct crypto_aead, base);165}166 167/**168 * crypto_alloc_aead() - allocate AEAD cipher handle169 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the170 * AEAD cipher171 * @type: specifies the type of the cipher172 * @mask: specifies the mask for the cipher173 *174 * Allocate a cipher handle for an AEAD. The returned struct175 * crypto_aead is the cipher handle that is required for any subsequent176 * API invocation for that AEAD.177 *178 * Return: allocated cipher handle in case of success; IS_ERR() is true in case179 * of an error, PTR_ERR() returns the error code.180 */181struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);182 183static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)184{185 return &tfm->base;186}187 188/**189 * crypto_free_aead() - zeroize and free aead handle190 * @tfm: cipher handle to be freed191 *192 * If @tfm is a NULL or error pointer, this function does nothing.193 */194static inline void crypto_free_aead(struct crypto_aead *tfm)195{196 crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));197}198 199/**200 * crypto_has_aead() - Search for the availability of an aead.201 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the202 * aead203 * @type: specifies the type of the aead204 * @mask: specifies the mask for the aead205 *206 * Return: true when the aead is known to the kernel crypto API; false207 * otherwise208 */209int crypto_has_aead(const char *alg_name, u32 type, u32 mask);210 211static inline const char *crypto_aead_driver_name(struct crypto_aead *tfm)212{213 return crypto_tfm_alg_driver_name(crypto_aead_tfm(tfm));214}215 216static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)217{218 return container_of(crypto_aead_tfm(tfm)->__crt_alg,219 struct aead_alg, base);220}221 222static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)223{224 return alg->ivsize;225}226 227/**228 * crypto_aead_ivsize() - obtain IV size229 * @tfm: cipher handle230 *231 * The size of the IV for the aead referenced by the cipher handle is232 * returned. This IV size may be zero if the cipher does not need an IV.233 *234 * Return: IV size in bytes235 */236static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)237{238 return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));239}240 241/**242 * crypto_aead_authsize() - obtain maximum authentication data size243 * @tfm: cipher handle244 *245 * The maximum size of the authentication data for the AEAD cipher referenced246 * by the AEAD cipher handle is returned. The authentication data size may be247 * zero if the cipher implements a hard-coded maximum.248 *249 * The authentication data may also be known as "tag value".250 *251 * Return: authentication data size / tag size in bytes252 */253static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)254{255 return tfm->authsize;256}257 258static inline unsigned int crypto_aead_alg_maxauthsize(struct aead_alg *alg)259{260 return alg->maxauthsize;261}262 263static inline unsigned int crypto_aead_maxauthsize(struct crypto_aead *aead)264{265 return crypto_aead_alg_maxauthsize(crypto_aead_alg(aead));266}267 268/**269 * crypto_aead_blocksize() - obtain block size of cipher270 * @tfm: cipher handle271 *272 * The block size for the AEAD referenced with the cipher handle is returned.273 * The caller may use that information to allocate appropriate memory for the274 * data returned by the encryption or decryption operation275 *276 * Return: block size of cipher277 */278static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)279{280 return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));281}282 283static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)284{285 return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));286}287 288static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)289{290 return crypto_tfm_get_flags(crypto_aead_tfm(tfm));291}292 293static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)294{295 crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);296}297 298static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)299{300 crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);301}302 303/**304 * crypto_aead_setkey() - set key for cipher305 * @tfm: cipher handle306 * @key: buffer holding the key307 * @keylen: length of the key in bytes308 *309 * The caller provided key is set for the AEAD referenced by the cipher310 * handle.311 *312 * Note, the key length determines the cipher type. Many block ciphers implement313 * different cipher modes depending on the key size, such as AES-128 vs AES-192314 * vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128315 * is performed.316 *317 * Return: 0 if the setting of the key was successful; < 0 if an error occurred318 */319int crypto_aead_setkey(struct crypto_aead *tfm,320 const u8 *key, unsigned int keylen);321 322/**323 * crypto_aead_setauthsize() - set authentication data size324 * @tfm: cipher handle325 * @authsize: size of the authentication data / tag in bytes326 *327 * Set the authentication data size / tag size. AEAD requires an authentication328 * tag (or MAC) in addition to the associated data.329 *330 * Return: 0 if the setting of the key was successful; < 0 if an error occurred331 */332int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);333 334static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)335{336 return __crypto_aead_cast(req->base.tfm);337}338 339/**340 * crypto_aead_encrypt() - encrypt plaintext341 * @req: reference to the aead_request handle that holds all information342 * needed to perform the cipher operation343 *344 * Encrypt plaintext data using the aead_request handle. That data structure345 * and how it is filled with data is discussed with the aead_request_*346 * functions.347 *348 * IMPORTANT NOTE The encryption operation creates the authentication data /349 * tag. That data is concatenated with the created ciphertext.350 * The ciphertext memory size is therefore the given number of351 * block cipher blocks + the size defined by the352 * crypto_aead_setauthsize invocation. The caller must ensure353 * that sufficient memory is available for the ciphertext and354 * the authentication tag.355 *356 * Return: 0 if the cipher operation was successful; < 0 if an error occurred357 */358int crypto_aead_encrypt(struct aead_request *req);359 360/**361 * crypto_aead_decrypt() - decrypt ciphertext362 * @req: reference to the aead_request handle that holds all information363 * needed to perform the cipher operation364 *365 * Decrypt ciphertext data using the aead_request handle. That data structure366 * and how it is filled with data is discussed with the aead_request_*367 * functions.368 *369 * IMPORTANT NOTE The caller must concatenate the ciphertext followed by the370 * authentication data / tag. That authentication data / tag371 * must have the size defined by the crypto_aead_setauthsize372 * invocation.373 *374 *375 * Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD376 * cipher operation performs the authentication of the data during the377 * decryption operation. Therefore, the function returns this error if378 * the authentication of the ciphertext was unsuccessful (i.e. the379 * integrity of the ciphertext or the associated data was violated);380 * < 0 if an error occurred.381 */382int crypto_aead_decrypt(struct aead_request *req);383 384/**385 * DOC: Asynchronous AEAD Request Handle386 *387 * The aead_request data structure contains all pointers to data required for388 * the AEAD cipher operation. This includes the cipher handle (which can be389 * used by multiple aead_request instances), pointer to plaintext and390 * ciphertext, asynchronous callback function, etc. It acts as a handle to the391 * aead_request_* API calls in a similar way as AEAD handle to the392 * crypto_aead_* API calls.393 */394 395/**396 * crypto_aead_reqsize() - obtain size of the request data structure397 * @tfm: cipher handle398 *399 * Return: number of bytes400 */401static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)402{403 return tfm->reqsize;404}405 406/**407 * aead_request_set_tfm() - update cipher handle reference in request408 * @req: request handle to be modified409 * @tfm: cipher handle that shall be added to the request handle410 *411 * Allow the caller to replace the existing aead handle in the request412 * data structure with a different one.413 */414static inline void aead_request_set_tfm(struct aead_request *req,415 struct crypto_aead *tfm)416{417 req->base.tfm = crypto_aead_tfm(tfm);418}419 420/**421 * aead_request_alloc() - allocate request data structure422 * @tfm: cipher handle to be registered with the request423 * @gfp: memory allocation flag that is handed to kmalloc by the API call.424 *425 * Allocate the request data structure that must be used with the AEAD426 * encrypt and decrypt API calls. During the allocation, the provided aead427 * handle is registered in the request data structure.428 *429 * Return: allocated request handle in case of success, or NULL if out of memory430 */431static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,432 gfp_t gfp)433{434 struct aead_request *req;435 436 req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);437 438 if (likely(req))439 aead_request_set_tfm(req, tfm);440 441 return req;442}443 444/**445 * aead_request_free() - zeroize and free request data structure446 * @req: request data structure cipher handle to be freed447 */448static inline void aead_request_free(struct aead_request *req)449{450 kfree_sensitive(req);451}452 453/**454 * aead_request_set_callback() - set asynchronous callback function455 * @req: request handle456 * @flags: specify zero or an ORing of the flags457 * CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and458 * increase the wait queue beyond the initial maximum size;459 * CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep460 * @compl: callback function pointer to be registered with the request handle461 * @data: The data pointer refers to memory that is not used by the kernel462 * crypto API, but provided to the callback function for it to use. Here,463 * the caller can provide a reference to memory the callback function can464 * operate on. As the callback function is invoked asynchronously to the465 * related functionality, it may need to access data structures of the466 * related functionality which can be referenced using this pointer. The467 * callback function can access the memory via the "data" field in the468 * crypto_async_request data structure provided to the callback function.469 *470 * Setting the callback function that is triggered once the cipher operation471 * completes472 *473 * The callback function is registered with the aead_request handle and474 * must comply with the following template::475 *476 * void callback_function(struct crypto_async_request *req, int error)477 */478static inline void aead_request_set_callback(struct aead_request *req,479 u32 flags,480 crypto_completion_t compl,481 void *data)482{483 req->base.complete = compl;484 req->base.data = data;485 req->base.flags = flags;486}487 488/**489 * aead_request_set_crypt - set data buffers490 * @req: request handle491 * @src: source scatter / gather list492 * @dst: destination scatter / gather list493 * @cryptlen: number of bytes to process from @src494 * @iv: IV for the cipher operation which must comply with the IV size defined495 * by crypto_aead_ivsize()496 *497 * Setting the source data and destination data scatter / gather lists which498 * hold the associated data concatenated with the plaintext or ciphertext. See499 * below for the authentication tag.500 *501 * For encryption, the source is treated as the plaintext and the502 * destination is the ciphertext. For a decryption operation, the use is503 * reversed - the source is the ciphertext and the destination is the plaintext.504 *505 * The memory structure for cipher operation has the following structure:506 *507 * - AEAD encryption input: assoc data || plaintext508 * - AEAD encryption output: assoc data || ciphertext || auth tag509 * - AEAD decryption input: assoc data || ciphertext || auth tag510 * - AEAD decryption output: assoc data || plaintext511 *512 * Albeit the kernel requires the presence of the AAD buffer, however,513 * the kernel does not fill the AAD buffer in the output case. If the514 * caller wants to have that data buffer filled, the caller must either515 * use an in-place cipher operation (i.e. same memory location for516 * input/output memory location).517 */518static inline void aead_request_set_crypt(struct aead_request *req,519 struct scatterlist *src,520 struct scatterlist *dst,521 unsigned int cryptlen, u8 *iv)522{523 req->src = src;524 req->dst = dst;525 req->cryptlen = cryptlen;526 req->iv = iv;527}528 529/**530 * aead_request_set_ad - set associated data information531 * @req: request handle532 * @assoclen: number of bytes in associated data533 *534 * Setting the AD information. This function sets the length of535 * the associated data.536 */537static inline void aead_request_set_ad(struct aead_request *req,538 unsigned int assoclen)539{540 req->assoclen = assoclen;541}542 543#endif /* _CRYPTO_AEAD_H */544